Preliminary results from field evalua3on of programmable thermostats: Does usability ma7er for energy savings?

Transcription

1 Preliminary results from field evalua3on of programmable thermostats: Does usability ma7er for energy savings? Olga Sachs, Ph.D. Kurt Roth, Ph.D.

2 Fraunhofer CSE Applied R&D and Technology Commercializa3on Applied R&D laboratory in Cambridge, MA Dedicated to research on and commercializadon of sustainable energy technologies Contract research for industry and government clients Focus on building technologies, solar photovoltaics (PV), and technology commercializadon ConfidenDal co- development programs Third- party technology validadon Technology commercializadon assistance for early- stage cleantech companies Targeted research inidadves to promote the profitability and technical leadership of U.S. industry Building Energy Efficiency Photovoltaic Module Technology Technology Commercializa3on

3 Building Energy Efficiency Group Focus Areas and Capabili3es Core Focus Areas: n Building Enclosures n ResidenDal Energy Management Cross- CuJng Capabili3es n Energy Modeling n Field Monitoring and EvaluaDon n Technology Assessment and Energy ConsumpDon CharacterizaDon Fraunhofer USA

4 Overview Thermostats and saving energy Usability of programmable thermostats Fraunhofer project to evaluate how thermostat usability affects energy- saving behavior Our results in the context of behavior change model

5 Thermostats & Energy Saving Programmable thermostats have large energy savings potendal: HeaDng and cooling comprise 42% of total source residendal energy Rule of thumb: 3% reducdon in energy use for each degree of reducdon in setpoint temperature Most U.S. households own either a programmable (37%) or manual (48%) thermostat (if they know what that means) Source: DOE/EIA.

6 Thermostats & Energy Saving Thermostat effecdveness depends on home occupant behavior: Programming for energy savings is complicated: Weekday/weekend, 7- day, vacadon Small fonts/bu7ons, abbreviadons Confusing symbols and lights MisconcepDons about energy and thermostats HeaDng all the Dme is more efficient than turning heat off Thermostat is simply an on/off switch Thermostat is a dimmer switch for heat Source: A. Meier et al. (2011)

7 Thermostats & Energy Saving Energy savings due to programmable thermostats: Programmable thermostats save energy 6% and 3.6% savings in a billing analysis of 7,000 and 25,000 households, respecdvely 9% savings in a survey of 2,300 respondents Programmable thermostats do not save energy No significant savings in billing and survey analysis of 299 households No savings and/or some increases Sources: RLW AnalyDcs (2007), Michaud et al. (2009), Tachibana (2009), Nevius & Pigg (1999), Cross & Judd (1996), Conner (2001), Parker 2000)

8 Current focus: Thermostat usability Development of new specificadons for EnergyStar: Main assumpdon: Improved usability will facilitate energy saving behavior Main quesdons: How to measure usability of programmable thermostats? How usability affects use and adopdon of thermostat energy saving features?

9 Current focus: Thermostat usability Usability tests at LBNL (A.Meier et al.): 5 thermostat interfaces 31 pardcipants 2 intefaces per person 6 tasks for each test 372 videos

10 Current focus: Thermostat usability Usability tests at LBNL (A.Meier et al.):

11 Current focus: Thermostat usability Findings from usability tests at LBNL (A.Meier et al.): Touchscreen interface performed be7er than bu7on interface Best- performing thermostat requires internet (WiFi) and computer Second best is Honeywell VisionPro

12 Does usability facilitate energy saving behavior? U.S. Department of Energy (DOE), Building America project Field EvaluaDon Study Research quesdon: Are people with a high- usability thermostat more likely to use energy- saving sejngs?

13 Fraunhofer Project MulDfamily affordable housing building in Revere, MA WeatherizaDon in endre building Furnace/AC replacement, insuladon and air- sealing of the back wall in the udlity closet Opt- out recruitment 83 out of 92 households pardcipated in the study 63 valid datasets

14 Fraunhofer Project Touch screen (high- usability) thermostats Bu7on interface (low- usability thermostats) Non- intrusive sensors to measure Temperature Humidity Furnace on/off state QuesDonnaire data Gas meter readings Weather data (Boston) Temperature in F Date

15 Two thermostat groups high usability touch screen VisionPro 8000 (VP) $118 low usability bu7on interface Basic Programmable (BA) $17

16 Same default sejngs $118 $17

17 Results: Night temp setback or not? T mean BA VP Mean [ F] Std. dev. [ F]

18 Results: Night temp setback or not? T min BA VP Mean [ F] Std. dev. [ F]

19 Results: Coldest nights Only nights when temperature fell below freezing 32 F (22 nights arer January 12) Calculated average temperature for each apartment between midnight and 4AM Averaged for 22 cold nights

20 Results: Coldest nights

21 Results: Coldest nights Average night temperature across 22 cold nights: BA VP Tmean ( F) Std.dev. ( F) Average evening temperature 8-10PM: BA VP Tmean ( F) Std.dev. ( F)

22 To be released this summer and fall Percentage of households in each condidon that used daydme setbacks Some program (default or not) Overrides of default sejng and the temp preferred Permanent Hold funcdon and for how long RelaDonship between self- report and sensor- based data SaDsfacDon with thermostats

23 What does it all mean? Factors underlying Behavior Change: Ability Trigger MoDvaDon Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this nodce and the full citadon on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Persuasive 09, April 26-29, Claremont, California, USA.

24 Thermostat behavior change: ability is not enough Three main factors: Ability Trigger MoDvaDon

25 Preliminary Conclusions Are people with a high- usability thermostat more likely to use energy- saving sejngs? Not, unless they are modvated and triggered What do we do next? Work on the missing components: modvadon & triggers Have technology replace modvadon and triggers